Acquisitions (Narrative) (Details) $ in Millions	Dec. 16, 2016 USD ($) ft² a MW	Jun. 06, 2016 USD ($) ft² a MW
Fort Worth Facility
Business Acquisition [Line Items]
Date of acquisition	Dec. 16, 2016
Acquisition costs | $	$ 50.1
Acres of real estate property | a	53
Area of facility (in square feet)	262,000
Fort Worth Facility | Basis Of Design With Eight MW Available Power [Member]
Business Acquisition [Line Items]
Area of facility (in square feet)	80,000
Capacity of the plant (in MW) | MW	8
Fort Worth Facility | Additional Critical Power [Member]
Business Acquisition [Line Items]
Capacity of the plant (in MW) | MW	8
Piscataway Facility
Business Acquisition [Line Items]
Date of acquisition		Jun. 06, 2016
Acquisition costs | $		$ 125.8
Acres of real estate property | a		38
Area of facility (in square feet)		360,000
Piscataway Facility | Raised Floor With 18 MW of Critical Power
Business Acquisition [Line Items]
Area of facility (in square feet)		89,000
Capacity of the plant (in MW) | MW		18
Piscataway Facility | Additional Raised Floor With 8 MW of Additional Critical Power
Business Acquisition [Line Items]
Area of facility (in square feet)		87,000
Capacity of the plant (in MW) | MW		8